Summits of Karakoram Mountain Range as seen from the Karakoram Highway near Nagar, Gilgit.

The Karakoram Highway, also known as the Friendship Highway in China, was built by the governments of Pakistan and China. It was started in 1959 and was completed and opened to the public in 1979. About 810 Pakistanis and about 200 Chinese workers lost their lives,[7] mostly in landslides and falls, while building the highway. The Chinese workers who died during the construction are buried in the Chinese cemetery in Gilgit. The route of the KKH traces one of the many paths of the ancient Silk Road.

On the Pakistani side, the road was constructed by FWO (Frontier Works Organisation), employing the Pakistan Army Corps of Engineers. The Engineer-in-Chief's Branch of the Pakistani Army completed a project documenting the history of the highway. The book History of Karakoram Highway was written by Brigadier (Retired) Muhammad Mumtaz Khalid in two volumes. In the first volume the author discusses the land and the people, the pre-historic communication system in the Northern Areas, the need for an all-weather road link with Gilgit, and the construction of Indus Valley Road. The second volume records events leading to the conversion of the Indus Valley Road to the Karakoram Highway, the difficulties in its construction, and the role of Pakistan Army Corps of Engineers and their Chinese counterparts in its construction.[8]

The highway cuts through the collision zone between the Eurasian and Indian plates, where China, Tajikistan, Afghanistan, and Pakistan come within 250 kilometres (160 mi) of each other. Owing largely to the extremely sensitive state of the Kashmir conflict between India and Pakistan, the Karakoram Highway has strategic and military importance to these nations, but particularly Pakistan and China.

On 4 January 2010, the KKH was closed in the Hunza Valley, eliminating through traffic to China except by small boats. A massive landslide 15 kilometres (9.3 mi) upstream from Hunza's capital of Karimabad created the potentially unstable Attabad Lake, which reached 22 kilometres (14 mi) in length and over 100 metres (330 ft) in depth by the first week of June 2010 when it finally began flowing over the landslide dam. The landslide destroyed parts of villages while killing many inhabitants. The subsequent lake displaced thousands and inundated over 20 kilometres (12 mi) of the KKH including the 310 metres (1,020 ft) long KKH bridge 4 kilometres (2.5 mi) south of Gulmit.[9][10][11]

It is highly questionable whether the lake, which reached 27 kilometres (17 mi) in length in 2011, will drain. Goods from and to further north are transported over the lake by small vessels, to be reloaded onto trucks at the other end.[12] In July 2012 Pakistan began constructing a revised route around the lake at a higher elevation with five new tunnels, with total length of 7.12 km, and two new bridges. The work was contracted out to the China Road & Bridge Corporation (CRBC) and was completed in September 2015—see Karakorum Highway Realignment (China-Pakistan Friendship Tunnels) below.[13]

Highlighted in red is the route of National Highway 35, which is to be completely rebuilt and upgraded under the CPEC agreement. Highlighted in blue is the 175 kilometre road between Gilgit and Skardu which is to be upgraded to a 4-lane highway.

As part of the $46 billion China Pakistan Economic Corridor, reconstruction and upgrade works on the Pakistani portion of the Karakoram Highway (KKH) are underway. The KKH spans the 887 kilometre long distance between the China-Pakistan border and the town of Burhan, near Hasan Abdal. At Burhan, the existing M1 motorway will intersect the Karakoram Highway at the Shah Maqsood Interchange. From there, access onwards to Islamabad and Lahore continues as part of the existing M1 and M2 motorways, while Burhan will also be at intersection of the Eastern Alignment, and the Western Alignment which will lead towards the port city of Gwadar.

A large section of the highway was damaged by landslides in 2010 that created Attabad Lake. The resulting landslides cut off both the Indus River and Karakoram Highway resulting in the formation of the reservoir. Prior to completion of the bypass, all vehicular traffic had to be loaded onto barges to traverse the new reservoir. Construction of the tunnels began in 2012 and required 36 months for completion. The 24 km long series of bridges and tunnels was inaugurated on 15 September 2015 at a cost of $275 million and was hailed as a major accomplishment.[14][15] The route comprises 5 tunnels and several bridges. The longest tunnel is 3360m, followed by 2736m, 435m, 410m and 195m, while the Shishkat Great Bridge on Hunza River is 480m long. The realignment restored the road link between Pakistan and China.

The Chinese section of the Karakoram Highway follows the north-south Sarykol ("Yellow Lake") valley just west of the Tarim Basin. The road from Kashgar goes southwest about 80 kilometres (50 mi) and then turns west to enter the Gez (Ghez) River canyon between Chakragil mountain on the north and Kongur mountain on the south. From the Gez canyon the population becomes Kirgiz. Having climbed up to the valley, the road turns south past Kongur, Karakul Lake, and Muztagh Ata on the east. Below Muztagh Ata, a new road goes west over the Kulma Pass to join the Pamir Highway in Gorno-Badakhshan, Tajikistan. The main road continues over a low pass (where the population becomes Tajik) and descends to Tashkurgan. Further south, a valley and jeep track leads west toward the Wakhjir Pass to the Wakhan Corridor. Next the road turns west to a checkpost and small settlement at Pirali, and then the Khunjerab Pass, beyond which is Pakistan, the Khunjerab River and Hunza.

In recent years the highway has sought to become a 'niche' adventure tourism destination although Pakistan attracts very few international tourists. Only Pakistanis and overseas citizens of Pakistani origin tend to visit these areas, and that too in small numbers. As of 2014, no Western tourist agency offers organised tours to the KKH. Western diplomats based in Pakistan are prohibited by their governments from making personal trips to these areas. The KKH was however ranked in 2006 as the "third best" tourist destination in Pakistan by The Guardian.[16] The road has given mountaineers and cyclists easier access to the many high mountains, glaciers, and lakes in the area. The highway provides access to Gilgit and Skardu from Islamabad by road. These are the two major hubs for mountaineering expeditions in the Gilgit–Baltistan region of Pakistan-administered Kashmir.[17] The Gilgit–Baltistan Administration of Pakistan-administered Kashmir and the Xinjiang Administration of China have signed an agreement to issue border passes to their permanent residents. This pass is valid for a calendar year and is used to travel through Khunjerab Pass only. Karakoram Highway is now one of the most beautiful destination in the world. KKH provides crosss country road trip from Hassan Abdal Pakistan to Kashghar. [18]

Karakoram Highway provides the pathway to expeditions for almost all peaks in Gilgit–Baltistan, Kashmir and several peaks in Xinjiang China. The region includes some of the world's largest glaciers like the Baltoro Glacier. Five of the Eight-thousanders (mountains taller than 8,000 metres (26,000 ft)) of the world that are in Pakistan are accessible by the highway. The notable mountains that can be directly seen while travelling on the highway are:

There are more than 50,000 pieces of rock art and petroglyphs all along the highway that are concentrated at ten major sites between Hunza and Shatial. The carvings were left by invaders, traders, and pilgrims who passed along the trade route, as well as by locals. The earliest date back to between 5000 and 1000 BC, showing single animals, triangular men, and hunting scenes in which the animals are larger than the hunters. These carvings were pecked into the rock with stone tools and are covered with a thick patina that yields their age.

There are several transport companies in Pakistan that offer bus service between major towns of the highway and from Rawalpindi and Lahore. The largest company is Northern Areas Transport Corporation (NATCO). Other companies are Masherbrum Travel, Silk Route Travel, K-2 movers, Anchan Travel, and Saeed Travel.

The KKH is best travelled in the spring or early autumn. Heavy snow during harsh winters can shut the highway down for extended periods. Heavy monsoon rains around July and August cause occasional landslides that can block the road for hours or more. The border crossing between China and Pakistan at Khunjerab Pass is open only between 1 May and 31 December.